1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device of high quality which enhances display quality by enhancing the numerical aperture and suppressing regions where a domain occurs.
2. Description of the Related Art
A so-called lateral electric field type (IPS type) liquid crystal display device is constituted such that on each pixel region formed on a liquid crystal side surface of one of substrates which are arranged to face each other with liquid crystal sandwiched therebetween, a pixel electrode and a counter electrode which generates an electric field between the pixel electrode and the counter electrode are formed, and liquid crystal is activated by components of the electric field including parallel to the substrate.
In the active matrix type liquid crystal display device to which such a structure is applied, first of all, on the liquid crystal side surface of one substrate, respective regions which are surrounded by a plurality of juxtaposed gate signal lines and a plurality of juxtaposed drain signal lines which cross these gate signal lines constitute pixel regions.
Then, each pixel region includes a thin film transistor which is operated in response to a scanning signal from the gate signal line, the pixel electrode to which a video signal is supplied from a drain signal line through the thin film transistor, and the counter electrode to which a signal which becomes reference with respect to the video signal is supplied.
Here, the pixel electrode and the counter electrode are formed in a strip-like pattern which extends in one direction, wherein the respective electrodes are usually constituted of two or more electrodes and are alternately arranged.
Further, in such a constitution, following type of liquid crystal display device is known, that is the counter electrodes are formed on an upper surface of an insulation film formed to cover also the drain signal lines and, at the same time, the counter electrodes are formed along the drain signal lines such that the counter electrodes have the center axes thereof substantially aligned with the drain signal lines and have a width larger than a width of the drain signal lines. This is because those lines of electric force from the drain signal lines can be easily terminated at the counter electrodes disposed above the drain signal lines and it is possible to prevent the lines of electric forces from being terminated to the pixel electrodes. That is, when lines of electric forces are terminated at the pixel electrodes, this gives rise to noises.
Then, the respective counter electrodes are formed integrally with counter voltage signal lines formed on an upper surface of the insulation film on the same layer and reference signals are supplied to respective counter electrodes through these counter voltage signal lines.
Further, there has been known a liquid crystal display device which adopts a so-called multi-domain system in which the pixel electrodes and the counter electrodes which are alternately arranged are formed in a pattern in which these electrodes have a large L-shaped bent portion.
With respect to liquid crystal, even when the molecular arrangement is at the same state, the polarized state of transmitting light is changed in response to the incident direction of light which is incident on a liquid crystal display panel and hence, optical transmissivity differs corresponding to the incident direction of light.
Such viewing-angle dependency of the liquid crystal display panel induces a luminance inversion phenomenon when a viewing point is obliquely inclined with respect to a viewing angle direction and hence, the liquid crystal display panel exhibits display characteristics that images are colored in a case of color display.
Accordingly, the pixel electrode is formed in a pattern in which at least one bent portion is formed in the extending direction and the counter electrode is formed in a shape which shifts this pattern in parallel, and using an imaginary line which connects bent points of these respective electrodes as a boundary, the direction of an electric field acting between respective electrodes differ between one region and the other region whereby coloring of images dependent on the viewing angle is compensated.